Significant dark current suppression in perovskite photodetectors using hole transport materials of lithium-doped vanadium oxide

Suppressing dark current density (Jdark) is one of most important strategies for improving responsivity (R), detectivity (D*), and linear dynamic rang (LDR) of perovskite photodetectors (PDs). However, the modulation mechanism of intrinsic and interfacial features of hole transport materials (HTMs) on their photodetection performance remains unclear and is related to complicated factors, resulting in perovskite PDs to generally suffer from high Jdark. In this study, we systematically investigated the effect of Li-doped VOX on the photodetection performance of perovskite PDs. The Li-doped VOX HTMs showed superior conductivity, high transmittance, and enlarged interfacial adhesion between the HTMs and perovskite layer. The PDs based on Li-doped VOX HTMs exhibited at least two orders lower Jdark and almost 1.6 times greater photocurrent densities (Jph) compared with those based on pristine VOX HTMs, while significantly maintained high external quantum efficiency (∼84 %) and impressive Dmax* of 1.23 × 1013 Jones. The enlarged surface roughness of Li-doped VOX HTMs leads to the enhancement of the interfacial adhesion between the HTMs and perovskite layer, which decreases the defects density of perovskite layer and trap-assisted recombination inside PDs, thus resulting in the significant suppression of Jdark and the improved collection of photoinduced charges. Overall, our findings provide a facial way to suppress Jdark for enhancing device performance of PDs.